SDL: Fixed thread-safety warning

SDL Commits
1 
From 0f80d47bbd0bf8bf4488038dfa680b29a5cb12a4 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 25 Aug 2023 08:21:54 -0700
Subject: [PATCH] Fixed thread-safety warning

---
 src/joystick/hidapi/SDL_hidapijoystick.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/joystick/hidapi/SDL_hidapijoystick.c b/src/joystick/hidapi/SDL_hidapijoystick.c
index bf045ca5d686..06e6d2607a0c 100644
--- a/src/joystick/hidapi/SDL_hidapijoystick.c
+++ b/src/joystick/hidapi/SDL_hidapijoystick.c
@@ -663,6 +663,8 @@ static void HIDAPI_UpdateJoystickSerial(SDL_HIDAPI_Device *device)
 {
     int i;
 
+    SDL_AssertJoysticksLocked();
+
     for (i = 0; i < device->num_joysticks; ++i) {
         SDL_Joystick *joystick = SDL_GetJoystickFromInstanceID(device->joysticks[i]);
         if (joystick && device->serial) {